During recent years interventional ultrasound diagnosis and therapy has become widely used, and many surgical procedures have been replaced by more gentle and less time consuming needle therapy to the benefit of the patient. Inter alia, ultrasonic imaging of maternal and fetal tissues has greatly facilitated prenatal diagnosis and treatment, and ultrasound imaging devices greatly assist the physician in properly positioning a biopsy needle to perform amniocentesis, cordocentesis and trans-abdominal chorionic sampling.
There are many different biopsy techniques and needles, and the needle depends on the type of patient and the target organ. The method mostly used today is the "free hand" technique, whereby the transducer is placed at a certain distance from the entry site of the needle and the needle is manipulated with one hand. This technique requires considerable skill and frequently repeated punctures, unless the target is relatively large or located superficially. For these reasons and because manipulation of the needle as guided by an ultrasound image requires both hands of the physician, there exists the trend to design and provide automatic devices for guiding the needle as directed by the ultrasound beam.
Early developed devices include a needle attached to an ultrasound transducer housing in spaced-apart, articulated manner, thus enabling the physician to manually direct the needle onto the desired biopsy location and to insert it to the required depth. Such devices are, for instance, disclosed in U.S. Pat. No. 4,899,756 (SONEC) and U.S. Pat. No. 4,911,173 (TERWILLINGER). While all of these devices provided some movement of the needle guide and needle relative to the transducer, the physician was significantly hampered in positioning the needle prior to and during insertion, as well in positioning the transducer once the needle had been inserted into the body.
A commonly used device includes a transducer and a coaxial needle guide for manual positioning and insertion of a needle. While these devices allow rapid and convenient guided biopsy, they have several significant drawbacks: 1) the transducer must be placed directly over the lesion which requires its sterilization or its draping by sterile covering. 2) The physician is forced to hold the transducer in one hand while using the other for sterilizing and anesthetizing the biopsy site. 3) After insertion of the needle the transducer must be held by an assistant or must be removed while the needle is maneuvered. 4) Multiple passes may necessitate re-positioning of the transducer and reinsertion of the needle. 5) The existing needle guides may make it difficult to enter some superficial lesion. 6) Most slotted transducers are linear in configuration and relatively large, making some costal and subcostal approaches difficult.
A completely automatic apparatus for computer controlled stereotactic brain surgery is disclosed in U.S. Pat. No. 5,078,140 (KWOH). This apparatus is highly complicated and expensive and, for this reason, available for large institutions only. It has to be calibrated for every operation, and does not belong into the category of the present apparatus designed for multiple, daily use by any physician who need not be specially skilled in this art.